Preparation and swelling properties of superabsorbent nanocomposites based on natural guar gum and organo-vermiculite

Vermiculite (VMT) was modified with cetyl trimethylammonium bromide (CTAB). Superabsorbent nanocomposites were prepared by solution polymerization of natural guar gum (GG), partially neutralized acrylic acid (NaA) and organo-vermiculite (CTA(+)-VMT), ammonium persulfate (APS) as initiator and N,N'-methylene-bis-acrylamide (MBA) as crosslinking agent. FTIR spectra confirmed that NaA had been grafted onto GG and the -OH groups of CTA(+)-VMT participated in the polymerization reaction. The intercalated-VMT was exfoliated during polymerization and uniformly dispersed in the GG-g-PNaA matrix. Swelling tests show that CTA(+)-VMT improved swelling and swelling rate more remarkably than VMT, and the nanocomposite exhibited distinct kinetic swelling behavior in NaCl and CaCl2 solution. Organo-VMT improved the gel strength of the nanocomposite compared to VMT, and the maximum storage modulus of the nanocomposite reached 658 Pa (gamma = 0.5%, omega = 100 rad/s). (C) 2009 Elsevier B.V. All rights reserved.